- Jun 4, 2018
Very interesting! You know... I've had several N54 headgaskets in my hand and never noticed that. Shame on me. (exposing the fact i'm not an engine guy lol) Absolutely agree, modern day stuff is so much different than the "old school" stuff. I assume all sorts of CFD was done on the block/head. Having said that, the CFD was done with a particular set of requirements, emissions and 300 BHP for example. We are now putting 1.5x to 2x the BHP through them in the aftermarket world so those requirements have now changed.Barry,
Keep in mind that the NA M motors have a MUCH lower heat flux than our engines do. Coolant flow into the N54 block is pretty symmetrical across Bank1/Bank2 , and the coolant passages in the HG actually get smaller as you move closer to cyl #1. I would imagine that, with the advent of modern FEA tools and unconstrained by using an all-new design, the NG6 motors should have pretty symmetrical coolant distribution across the cyls despite the lack of external cooling manifolds like in the S14/S54 above. FWIW the older Ferrari "Dino" V8s and V12s use a similar setup, its just the way things were done on race/hi-po engines back in the day before the advent of modern computer aided engineering tools.
@Hydra Performance do you have any experience with the two different n54 blocks where some have the coolant channel between cylinders (early ones I think) and then some have no passage between them? Do you have a preference?
Interesting note about the changes on the n55. I have Zero experience with those. But that is an excellent data point. I think I have seen those guys testing at NJMP before. I've been curious how the people running the M235Rs have fared with cooling. Seems like the n55 has less problems with cooling. The M235R clearly is going to have DME logic of a "performance" motor unlike our MSD81s. The guys racing the n20 motors have had all sorts of troubles. After going through many motors I think a mechanical water pump was part of the solution.I think another thing that should be noted in regard to the cooling logic is that there is an "economy mode" that MHD does not cover. They leave it unchanged in their cooling setting changes.The car rarely goes into economy mode, from what I've seen. It's definitely not applicable at all to a discussion about tuning cooling tables for a track car. It's not like the car is dropping into economy mode on the track as you coast around a corner (this might be what the literature you quoted is referencing).
I can't speak on cylinder head coolant flow other than it's an open deck. So long as the channels are "tuned" well there shouldn't be too much hot spotting, like you noted. However, BMW did revise quiet a bit of the oiling and cooling channels on the N55 over the outgoing N54. The head-gasket is significantly different. I did notice there is quiet a bit of overlap of the gasket over certain channels. They must'v seen improvements to be made to have casted a new block and cylinder head... No one at Pirelli world challenge seems to have any issues racing the M235iR cars (n55s). You might be able to contact classic BMW or something and see what they have to say in regard to coolant DME logic on those cars.